1. Field of the Invention
The present invention relates to an electronic apparatus and more particularly to an electronic timepiece whose time is set in accordance with a standard time and frequency signal.
2. Description of the Related Art
As one type of electronic apparatus, radio-controlled watches are known which receive the standard time and frequency signal and set the current times thereof automatically in accordance with the signal. In such watches, antennas that include a core made of ferrite or an amorphous magnetic material around which a coil is wound are widely used to receive the signal.
With a watch in which a motor drives the hands, the hand driving can be influenced by external magnetism undesirable for control of the watch, thereby reducing the time accuracy. In order to avoid such a situation, an anti-magnetic plate is provided within the case to screen out the external magnetism. Such anti-magnetic measures are also required even in radio-controlled watches having a hand-driving structure similar to that of general watches in order to maintain the watch accuracy.
The radio-controlled watch receives the standard time and frequency signal including time information, extracts the time information, sets the internal time thereof based on the time information, and then displays an accurate time. Thus, if the whole movement including the motor is covered with an anti-magnetic plate that screens out the external magnetism, it is, in turn, difficult to receive the standard time and frequency signal and hence the reception capacity may be possibly reduced.
In order to prevent a reduction in the reception capacity, an electronic watch has been proposed in which the movement including the motor is covered with an anti-magnetic plate with an opening through which a coil-bearing magnetic part of an antenna is exposed outside (see, for example, Published Unexamined Japanese Patent Application 2004-294258).
With this arrangement, a wide range of the case is covered with the anti-magnetic plate. Therefore, compared to the watch in which the anti-magnetic plate covers the coil bearing part of the antenna, the reception is somehow improved, but convergence of the magnetic flux of the received radio waves on the antenna is limited by the anti-magnetic plate. Hence, a great improvement of the reception cannot be expected.
It is therefore an object of the present invention to provide an electronic apparatus and timepiece free from influence of undesirable external magnetism and having high reception accuracy of the standard time and frequency signal.